The use of ultrasound, including high intensity focused ultrasound (HIFU) for therapeutic purposes has received significant attention in the medical community. During treatment, a portion of the mechanical energy from these high intensity sound waves is converted at the targeted location into thermal energy. The amount of thermal energy convened can be sufficiently intense to cauterize tissue, or to cause tissue necrosis (by inducing a temperature rise to beyond 70° C.). Importantly, the focal point of this energy deposition can be tightly controlled so as to obtain tissue necrosis in a small target area without damaging adjoining tissue. Thus, both benign and malignant tumors can be destroyed with HIFU without surgical exposure to the tumor site.
A particular advantage of HIFU therapy over certain traditional therapies is that HIFU is less invasive. Further advantages include reduced blood loss, reduced risk of infection, shorter hospital stays, and lower health care costs. HIFU has the potential to provide an additional treatment methodology consistent with this trend by offering a method of non-invasive surgery. For example, HIFU enables transcutaneous tumor treatment without making a single incision, thus avoiding blood loss and the risk of infection and with few side effects. Furthermore, HIFU therapy may be performed without the need for general anesthesia, thereby reducing surgical complications and cost. Most importantly, these treatments may be performed on an outpatient basis, further reducing health care cost, while increasing patient comfort.
The application of HIFU for the destruction of benign and malignant tumors in the neck area presents a relatively new direction in the field. Patients with thyroid and parathyroid tumors stand to benefit significantly from relatively non-invasive nature of HIFU. Further, among benign conditions of the neck area, thyroid nodules are frequently discovered during routine physical examination or during investigations for other purposes. Recently, systematic ultrasonographic exploration of a French large adult cohort indicated that 14.5% of subjects had nodular thyroid structures (Valeix el al. (2001), Ann Endocrinol (Paris) 62(6):499-506.) In the United States, 40% of the female population age 50 or older are presented with thyroid nodules at ultrasonography, and the prevalence of thyroid nodules increases throughout life. Patients presenting with such benign nodules are subject to long follow-up procedures and the best therapeutic strategy after the discovery of such nodules is still a matter of debate. Often, the goal of the physician becomes avoiding surgery and choosing among minimally invasive treatments which may be done in an ambulatory settings and result in fewer sides effects compared to surgery.
HIFU is a promising non-invasive procedure for treatment of the disorders of the neck tissue. However, the enduring problems of HIFU application remain in accurately assessing, targeting and monitoring ablated tissues during the therapeutic treatment. Specifically, application of HIFU to the wrong tissue in the neck of a patient can lead lower treatment efficacy and to various side effects, such as for example loss of voice, due to damaging the laryngeal nerves. Thus, in an attempt to circumvent the deficiencies in the art, there have been devices developed to attempt synchronization of HIFU energy with the movements of patients.
U.S. Reissued Pat. No. RE38.030 teaches a method of applying focused ultrasound to the thyroid of a patient. The method includes monitoring the movement of the patient during the focused ultrasound treatment, particularly at the trachea. Echo location is used to determine the position of a portion of the patient's body to identify a treatment zone. If a change in position is detected, an alarm signal is triggered and the position of the therapy device is changed. Thereby, the therapy on the thyroid is continued as the focused ultrasound is kept targeted on the thyroid.
RE38.030 is understood not specifically to disclose, teach or suggest movements in relation to swallowing, nor is it understood to disclose, teach or suggest a separate sensor for the detection of movement of the larynx. Moreover, RE38,030 also appears not to specifically disclose, teach or suggest the stoppage of signal from the focused ultrasound therapy device in response to patient movement including swallowing.
U.S. Pat. No. 6,076,005 is understood to be directed toward gating of therapeutic energy including sonic energy based on the respiratory cycle of the patient. The patient's lungs are monitored to provide quasi-continuous measurements of the actions of the patient's lungs. However, U.S. Pat. No. 6,076,005 is understood not to disclose, teach or suggest movements in relation to swallowing, nor does it teach a separate sensor for the detection of movement of the larynx. Further, U.S. Pat. No. 6,076,005 is also understood not to disclose, teach or suggest the stoppage of signal from the focused ultrasound therapy device in response to patient movement including swallowing.
Thus, there is understood a general need in the art to provide HIFU devices capable to deliver therapeutic energy to the correct tissue i.e. the thyroid or parathyroid, despite the movement of the tissue of the neck due to patient's swallowing or other movement during treatment.